This is why I don't watch Holby city lol. His piece looked decent though.

I mark the hairline with a comb, it does the job.

According to Da Vinci, the perfect symmetry, is the width from your chin to the bottom of your nose...should be the same width from eyebrows to hairline. But ppl have all sorts of hairlines, what works for me is scrunching up my forhead, where the wrinkles stop is where the hairline starts.